This invention relates to apparatus used in rig operations associated with the drilling, completion and servicing of oil and gas wells. With more particularity, this invention relates to an apparatus mounted on a drilling or workover rig, in particular on or near the floor of the rig, for positioning equipment in relation to the rig floor. The apparatus is especially suited for, but not limited to, positioning power tongs used to make up and break out threaded connections joining lengths of tubulars.
Positioning equipment above and around the floor of a drilling, workover or completion rig, to permit efficient and safe use, poses certain problems. One type of equipment which requires positioning at different heights above the rig floor, and at different positions with respect to the center of the rig floor, is power tongs. Power tongs are used to screw together (xe2x80x9cmakeupxe2x80x9d) and unscrew (xe2x80x9cbreak outxe2x80x9d) threaded connections which join lengths of tubulars, such as drill pipe. Power tongs, in general, are usually hydraulically powered rotary tongs capable of exerting great torque to make up and break out connections.
In addition, another type of power equipment used in connection with threaded tubulars is commonly referred to as xe2x80x9cbreak outxe2x80x9d tools, which are generally adapted to rather limited degree of rotation per xe2x80x9cbitexe2x80x9d on the threaded connection. While often having great torque capacity, the limited degree of rotation makes these tools generally unsuitable for spinning up and unspinning threaded connections, which task is usually accomplished by other tools.
For purposes of this application, the term xe2x80x9cpower tongxe2x80x9d encompasses both those power tools commonly referred to as power tongs, and also those tools commonly referred to as breakout tools, and encompasses such tools whether powered by hydraulics, pneumatics, electric motors, or some combination thereof.
Using as an example the makeup and breakout of drill pipe connections, the threaded connections themselves referred to as xe2x80x9ctool joints,xe2x80x9d some connections may be made up with the drill pipe in the slips of the rotary, therefore in one directional sense the connection is in the center of the rig floor. However, the height above the rig floor of the tool joint which must be gripped may vary from connection to connection. Therefore, even when the connection is in the center of the rig floor, it is necessary to be able to position power tongs at a desired height or elevation, which may vary from connection to connection. Other situations entail makeup and breakout of connections spaced away from the center of the rig floor, for example in the xe2x80x9cmouseholexe2x80x9d or xe2x80x9coff line hole.xe2x80x9d It can be readily seen that power tongs may be required to be positioned in a number of locations above and around the rig floor.
Traditionally, power tongs were hung from a cable fixed to the derrick or mast of the rig. A spring is connected to the lower end of the cable, then to a powered hydraulic lift cylinder, which then connects to the power tong. The hydraulic lift cylinder may be telescoped in and out to raise and lower the power tong to the desired level or height above the rig floor, to grasp the threaded connection. Power tongs may also be suspended from cables attached to airhoists. These traditional means of hanging a power tong permitted elevation adjustments, while to otherwise position the tong it to be pushed or pulled to the desired location (with respect to the center of the rig floor), by one or more rig personnel physically pushing or pulling the power tong (along with raising and lowering via the lift cylinder), as the case may be. Injuries have occurred as a result of the heavy tongs swinging on their cables and striking personnel.
Further problems arise in the positioning of power tongs on floating drilling vessels, such as semi-submersible drilling rigs and drill ships. Such rigs, depending upon weather and sea conditions, may have significant movement of the entire rig, tending to swing the power tongs back and forth. In addition to posing increased difficulty in positioning the power tongs in a desired elevation and location, it will be appreciated that personnel safety concerns are greatly increased, with a heavy piece of equipment swinging on a cable.
In addition to power tongs, other equipment and even personnel must be positioned above and around rig floors. Equipment and personnel are sometimes lifted on air hoist lines, with the attendant problems as described above for power tongs.
It is desirable, then, to have an apparatus, in the nature of a boom type positioner, adapted to be mounted in operable relationship to the floor of a drilling, completion or workover rig, which permits positive placement of equipment and personnel, and holding same in the desired position with respect to the center of the rig floor and an elevation above the rig floor. At the same time, the apparatus is mounted in a location and capable of being placed in a position that rig operations are not impeded when the positioner is not in use.
The invention comprises a rig mounted, power tong positioner, comprising a telescoping boom rotatably mounted on an upright member, which is in turn mounted on a pedestal mounted on the rig structure, preferably the rig substructure. The apparatus is adapted for use within the structure of the rig mast or derrick, and is adapted to position a rotary power tong at a desired position with respect to the center of the rig floor and elevation about the rig floor, including but not limited to positions above the rotary (or center) of the rig, the mousehole, or off line hole. The telescoping boom of the present invention provides lengthwise adjustment. A first end of the boom is rotatably mounted via a hinge on the upright member, and a second end of the boom (the end opposite the upright member) may thereby be raised and lowered (thereby moving in a plane substantially perpendicular to the rig floor) as the boom is rotated about its pivot point. The second end may be moved in a plane substantially parallel to the rig floor by rotation of the upright member. One embodiment of the invention further comprises a power tong mounted on the second end of the boom. Controls to position the boom, and hence the tong, are mounted on the power tong, in close proximity to the power tong controls, where the power tong operator can readily manipulate both sets of controls. Additional controls are mounted on or near the upright member to permit operation of the positioner and thus placement of the power tongs. Still further controls to operate the power tong unit itself may be mounted on or near the upright member, thereby permitting remote makeup and breakout of threaded connections. Other types of remote controls may be employed to operate the boom and tongs from still more remote locations, such as by radio frequency.